Apparatus for high-frequency dielectric progressive bonding



Dec. 27, 1955 G. T. HART 2,728,839

APPARATUS FOR HIGH-FREQUENCY DIELECTRIC PROGRESSIVE BONDING OriginalFiled June 28, 1946 4 Sheets-Sheet 1 In men for Geo/:96 Tficzr'zflDecdabeZ fffiamfAdmx: I a A n 9/1 Frequency 0505 [la for 1c PROGRESSIVEBONDING G. T. HART Dec. 27, 1955 APPARATUS FOR HIGH-FREQUENCY DIELECTR 4Sheets-Sheet 2 Original Filed June 28, 1946 [n pen for 660/196 THQPLDQCHMabel HHa/"z Dec. 27, 1955 HART 2,728,839

APPARATUS FOR HIGH-FREQUENCY DIELECTRIC PROGRESSIVE BONDING OriginalFiled June 28, 1946 4 Sheets-Sheet 3 El l 7 I r l I I P55521504 (4 Invenfor 50 z f ffyy 0): George THa/"zflDecd (g iawg q turn a ZDZZ H HQ/"Z,Admoc .l 6 (PEccen Zrz' c Under H'cssure I resser Ibo? cs. T. HART2,728,839

FREQUENCY DIELECTRIC PROGRESSIVE BONDING Dec. 27, 1955 APPARATUS FORHIGH 4 Sheets-$heet 4 Original Filed June 28, 1946 Oscillator" UnitedStates Patent O APPARATUS FOR HIGH-FREQUENCY DlELEC- TRIC PROGRESSIVEBONDING George T. Hart, deceased, late of Nahant, Mass., by Mabel H.Hart, administratrix, Nahant,-Mass., assignor to United Shoe MachineryCorporation, Flemington, N. J., a corporation of New Jersey Originalapplication June 28, 1946, Serial No. 679,994,

now Patent No. 2,631,223, dated March 10, 1953. Divided andthisapplication December 9, 1952, Serial No. 324,964

12 Claims. (Cl. 219-1053),

This application, which is a division of my application Serial No.679,994, filed June 28, 1946, and entitled Apparatus for High-FrequencyDielectric Progressive Bonding, now United States Patent No. 2,631,223,issued March 10, 1953, relates to apparatus for progressively bondingplies of thermoplastic materials by subjecting the work to ahigh-frequency electric field. More particularly, it relates to a switchmechanism, for use with apparatus employing a reciprocatory electrode,to control the timing of the supply of high-frequency energy to theelectrode so that the energy is supplied to the electrode only while itis engaging the work.

It has been found that, where the supplyof high-frequency electricenergy to the electrode of a reciprocatory electrode bonding apparatusis continued during the lifting of the electrode from the surface of thework, arcing may occur between the electrode and the work withconsequent burning of and damage to the work.

Accordingly, an important object of this invention is the provision, ina reciprocatory electrode bonding machine, of switch mechanism connectedto control the supply of such energy and arranged to be operated inrelation to the movements of said electrode so that such energy issupplied to the electrode only during the time that it engages the work.

To this end, and in accordance with a feature of this invention shown inthe two illustrative embodiments, a spring-loaded lost motion connectionis provided between a vertically movable electrode carrier and a liftinglever (or a lifting member connected to the lever) arranged to bereciprocated by the drive shaft of .the machine, and

switch contacts are opera'tively associated withsaid con.- nection foroperation by relative movement. between the carrier and the lever ormember, tofbe closed upon'a predetermined yieldingjin saidconnectionconsequent' to pressure of the electrode against the work.

In accordance withanother feature of the invent-ion, means are providedfor adjusting the spring-loadingof such connection to-vary the electrodepressure upon the work and for adjusting the heightwise position. of theelectrode with respect to said connection for accommodating differentthicknesses of work or for varying the switching action with a giventhickness of work.-

The above and other objects, features and advantages of the inventionwill be appreciated more fully. from the following description andaccompanying drawings and will thereafter be pointed out in the appendedclaims.

in the drawings,

Fig. l is a sectional front elevation of a bonding machine embodying theinvention and employing electrodes which periodically feed the workwhile it is being heated and work-holding members which grip the heatedwork parts together in the intervening periods; 9

Fig. 1a is a front view of a swinging arm carryingv a lower electrode ofthe above machine;

Fig. 1b is a front view principally of a cam,'cam housing and a driveshaft of the same machine;

Fig. 2 is a partial left side elevation of the machine;

Fig. 3 is a partial right side elevation of the machine;

Fig. 4 is a partial sectional plan view taken on the line IV-IV in Fig.1 and illustrating the work engaging surfaces of the electrodes andwork-holding members of the machine;

Figs. 5a to 5d, inclusive, are views in elevation of the work-holdingmembers of the machine illustrating the positionalrelationships thereofat different points in their cycle of movement, the work being shown invertical section;

Fig. Se is a cam chart showing the timing of the driving action of a camand an eccentric in operating the work-holding member;

Fig. 6 is a front elevation of a modified bonding machine whereinreciprocatory electrode members operate to clamp and hold the work andwherein the work-holding and feeding members engage the work to advanceit during the period while the electrodes are apart;

Fig. 7 is a sectional plan view of the work-holding members of themachine of Fig. 6; and

Figs. 8a to 8d, inclusive, are views in elevation of such members inpositions characteristic of different points in their cycle of movement.

in Figs. 1, 2, 3 and 4, the invention is shown as embodied in a machinewherein electrode members 2 and 4 are adapted for feeding the work,while reciprocatory work-holding members 8, 9, are disposed at alocation forward of the electrode members. Such members are shownoperatively engaging the welt 3 and outsole 1 of a shoe in the processof manufacture, the welt and outsole having a layer of thermoactiveadhesive between them. It will be understood that either or both thewelt and outsole may be of synthetic material if desired. The outsole 1is being engaged by an insulated upper electrode 2 and the welt 3 isbeing engaged by lower electrode 4 which is grounded electrically to theframe 5' of the machine. Vertical movements of the electrode 2 arecontrolled by a driven cam 13, to be described later, while lateralmovements are imparted by an eccentric 59, both the cam and theeccentric being fixed to a driven shaft 10. In their indicatedpositions, the upper electrode 2 has just descended upon the workpreparatory to imparting thereto a right-to-left motion, and the presserfoot 8, comprising one of the work-holding members, has just left thework. A-lower member 9, comprising the other work-holding member, isbolted rigidly to the frame of the machine.

Movements ofthe electrodes 2 and 4, and of the presser foot 8 relativeto that of the eccentric 59 are illustrated by several positional viewsof such members. in Fig.- 5a the work is shown held firmly between thepresser foot 8 and the supporting member 9 while the electrode members 2and 4, are separated, at their half-way position in their returnleft-to-right movement, as indicated by the position of the ecentric 59.In Fig. 5b the presser foot 8 has. released the work and the electrodemembers 2 and 4 have closed upon the work and begun their right-to-leftfeeding movement,bodily carrying the work along with them as indicatedby the arrow and the changed position of the imperfections in the upperlayer of the work. In Fig. 5c the electrode members are shown as havingjust arrived at their left-most position and are about to separate fromthe work, the presser foot 8 having just descended and engaged the work.In Fig. 5d the electrode members have separated and started on theirreturn movement to the right.

As to the matter of imparting vertical movement to the electrode 2,driving power is imparted to the shaft 10 journaled in the frame 5 ofthe machine, which shaft carries the cam 13 retained in a cam housing 14(Fig. lb). Inside the cam housing, a pair of inwardly projecting platesand 16 engage the peripheral surface of the cam 13. The cam housing 14is retained in position lengthwise of the shaft 10 by means of acircular end plate (Fig. 2) and a corresponding circular plate 17abutting respectively against the back and front'sides of said housing.The circular plate 17 has an inclined groove 13 arranged for slidableengagement with an inclined diametral key or ridge 19 projecting fromthe front side of the cam housing 14, serving to guide the housing inits oscillatory movement which is derived from rotation of the cam.

The oscillatory movement of the housing 14 is conveyed through a drivinglink 22 to an upper offset rockcr arm 23 pivoted on an overhead shaft24. Integral with the offset arm 23, and bridging the front bearing 24'for the shaft 24, is a yoke 23 joining the rocker arm 23 to anoverhanging bifurcated arm 25 (Figs. 1 and 3) pivoted on the shaft 24and connected by a pin 28 to an upper collar 29. It will be seen thatthe arm 23,

yoke 23' and arm 25 together constitute a lifting lever .which may bereciprocated by rotation of the shaft 10 to impart a rising and fallingmovement to the collar 29. A sleeve 32 receives the cyclic downwardthrusts of the collar 29 upon adjustment nuts and 36 which are threadedonto the upper end of such sleeve, and these thrusts are transmitted,through a loaded spring 30 which is engaged at its upper end by aflanged member 31 abutting against the bottom end of the sleeve 32, toan electrode carrier comprising a vertical rod 39 slidable inside thecollar 29 and sleeve 32 axially thereof and carrying at its lower endthe upper electrode 2. The lower end of the spring 30 engages a flangedmember 37 which is seated on a shoulder 38 of the vertical rod 39. Thesleeve 32 in turn, slides inside a yoke member 62, as does the lowersection 38 of the rod 39. The sleeve 32 is prevented from turning by theaction of a pin 47 inserted through the yoke 62 and bearing against aflattened portion of the sleeve. The shouldered portion 38 has a lowerportion 42 which is rectangular in section and which is slotted anddovetailed at the bottom thereof, as shown, to receive and hold theelectrode assembly, particularly an insulating member 43 on which ismounted, by means of screws and 41, the electrode 2. A clamp bolt 44provides the gripping force necessary to hold securely the electrodeassembly when inserted into the dovetail.

As the collar 29 descends, as soon as resistance to downward movement ofthe electrode 2 exceeds the loading of the spring 30, the spring yields,allowing relative vertical movement between the collar 29 and the rod39. The precompression of the spring 30 accordingly determines thegripping pressure of the electrode members 2 and 4 against the work 1and 3, and adjustment thereof is made, either by adjusting theheightwise position of the stop nuts 45 and 46, which are carried at theupper end of the electrode carrier rod 39 for cooperating with the upperend of collar 29, thereby also raising or lowering the electrode 2, orby means of similarly adjusting lit the nuts 35 and 36 on the sleeve 32in which case the heightwise position of the electrode is not disturbed.Adjustment of the position of the upper electrode member 2 may be made,for example, for accommodating work of different thicknesses. It will beseen that there is thus provided between the collar 29 and the electrodemember 2 a spring-biased lost motion connection whose yield pressure maybe varied by the foregoing adjustments, either with or without adjustingthe electrode position.

To provide for supplying high-frequency electric energy to the electrodemembers only when they are in firm engagement with the work, a switch 49is mounted on the side of the upper collar 29. This switch, which may beof the type known as micro-switch," has a plunger 50 adapted upon veryshort movement, to open and close the switch contacts for breaking andmaking an electric circuit therethrough, depending on whether theplunger is either depressed against the pressure of a spring containedin the switch box or allowed to assume an extended position. The plunger50 is arranged to be actuated by a circular plate 51 mounted on theupper end of the rod 39. The plate 51 is secured on a threaded neckportion forming part of the nut 46 by means of a pair of nuts 52 whichscrew onto said neck portion on opposite sides of the plate 51.Switching action may accordingly be performed by relative movementbetween the circular plate 51 and the switch box 49, or in other wordsbetween the lifting lever and the electrode which takes place duringyielding of the spring 30. On the down stroke of the electrode 2, anoscillator 56 is made operative by the switch when the spring 30 yieldsunder the pressure of the electrode against the work, and on the upstroke, the reverse switching action takes place. The electrodes arethereby supplied with high-frequency electric energy only during thetime when they exert more than a predetermined pressure against thework. The vertical position of the circular plate 51 is adjustable onsaid rod 39 to adjust the timing of the aforesaid switch action, byadjusting the nuts 52 as well as by a repositioning of the nut 46.

The electrical connections shown include a pair of wires 53 running fromthe switch contacts to the highfrequency oscillator 56. These wires areconnected in a circuit (not shown) associated with the oscillator whichcircuit is adapted to turn the latter on and off. Highfrequency powerfrom the oscillator is conducted to the upper electrode 2 through aninsulated cable 54 having a connecting lug 55 screwed to a lateralextension of the electrode 2 and through a grounding wire 57 connectedbetween the oscillator ground terminal and a point 58 on the frame ofthe machine.

Lateral movement is imparted to -the electrode member 2 by the action ofthe eccentric 59 carried at the front end of the main drive shaft 10.The eccentric rotates in a U-shaped block 60 (Fig. l) which is inslidable engagement with a U-shaped slot 61 in the yoke member 62. Asthe eccentric rotates, the yoke member 62 is moved laterally back andforth through the action of the block 60 which, in one direction ofmovement, bears aganist the end of the slot 61 and, in the other,against a spring 65. The. spring 65 encircles a bolt 66 projectingoutwardly from the block 60 through a cover plate 67 bolted to the sideof the yoke 62 and the outer end of the spring is seated against thebottom of a recess in the cover plate 67. From the rotational motion ofthe cocentric 59, the yoke 62 derives not only the desired rocking andtransverse work feeding motion but additionally receives a verticalcomponent of motion which latter motion is superfluous to the electrodemovement and is therefore taken up by the sliding action of the yoke 62on the sleeve 32 and the enlarged section 38 of the rod 39. p

The lower electrode 4 is formed by the foot of an L- shaped arm 68 (Fig.1a) which is swingably suspended by the head 68 (Fig. 3) of a pin 69carried by a boss 69' in the frame of the machine directly behind thebifurcated arm 25. Lateral movement is given the arm 68. in such mannerthat the electrode 4 remains directly beneath the opposing upperelectrode 2, by means of a pin 70 in yoke 62' projecting rearwardly intoa slot 70' (Fig. 3') in the arm 68.

The presser foot 8 is carried'by a lug 86 projecting downwardlyfrom thebottom end of a slide member 84 which is slidably retained in a guideway84' on the front of the frame by a cover 85 held by screws. The slidemember 84 and thus the presser foot 8 receive vertical movement throughthe action of a lever 72 pivoted about a pin 73 inserted into the frontof the frame. Carried at one end of the lever 72, a pin 74 (Fig. 3)engages a slot 75 recessed into the upper backportion of the yoke 62therebyreciprocating the lever in accordance with vertical movements oftheyoke. Another pin 77 (Fig.

2) at the other end of the lever 72 engages a slot- 78 recessed into thehead section 79 of a rod 76'slidable in the slide member 84 whereby therod is connected to be raised and lowered by reciprocation of the lever.On the upward motion of the rod 76, stop collars 82 and 83 threaded onthe lower end of the rod 76 bear against the slide member 84, liftingthe latter positively. On the down motion, yielding downward force isprovided to the presser foot through compression of a spring 87 which atits upper end bears against a shoulder of the rod 76, while its lowerend bears against an annular ledge of the slide member 84. The spring 87may be adjustably precompressed or loaded by means of the threaded stopcollars 82 and 83.

It is preferred, although not essential, to construct the presser foot 8of insulating material since it thereby tends to minimize deflection ofthe high-frequency field existing between electrodes, especially whenthe latter are approaching the presser foot in their leftward travel tothe position shown in Fig. c, forward in the direction of feedingmovement. The same is true of support member 9. Suitable for thispurpose are Bakelite, hard rubber or other such materials of appropriatestrength and wear resistant qualities.

The lower electrode member 4 and the lower supporting member 9 haveoutwardly extending curved shoulder portions (Figs. 2 and 3) adapted forslidable engagement with the welt crease of the shoe, and, asillustrated in Fig. 4, these members are rounded off at the sidesthereof to facilitate free sliding movement of the shoe length- 9 wiseof the crease with respect to these members.

In order for the work to be held securely between the electrode membersfor movement of the work, the welt engaging surface of the lowerelectrode 4 is tapered (Fig. 1), being highest at its forward edge,which is directly beneath the upper electrode 2, and sloping offtherefrom gently toward the trailing edge. The heavily shaded sectionsin Fig. 4 represent the Work engaging areas viewed in a cross-section ofthe upper electrode 2 and the presser foot 8. The inside surface of theelectrode member 2 is shown substantially flush with the outside edge ofthe welt and outsole.

Fig. 5e shows the time relationship, in degrees of an operating cycle,between the movements produced by the cam 13 and the eccentric 59 inoperating the electrode and the presser foot. The reference, or 0,position is taken as that shown in Fig. 1.

It has been found convenient to maintain the electrodes at maximumclosing pressure, with the spring 30 compressed the maximum amount,during approximately 106 of the cam rotation cycle, allowing 74 thereoffor separating the upper electrode Zfrom the work, 106 for returning theelectrodes to their starting position, and 74 for lowering the electrode2 against the work and in creating full closing pressure between theelectrodes. It is to be noted that during a substantial portion 'of thelatter 74 period allowed for closure of the electrodes, progressiveyielding occurs in the spring 30; the reverse is true of the former 74period during which the electrodes are being separated from the work. Toprevent slack movement of the cam housing 14 with its plates 15 and 16,all diameters of the cam 13 through the axis of the shaft are madeequal, and are slightly less than the distance between the plates and16. Means (not shown) may be provided for angular adjustment of the camwith respect to the drive shaft 10 for proper cycling of the cam withrespect to the eccentric 59.

It will be observed from Fig. 52 that the switching of thehigh-frequency energy occurs during change of the pressure of theelectrode 2 upon the Work so that the energy is supplied to theelectrode only while it is engaging the work under pressure. It willalso be seen that the duration of the application of the energy isdetermined by the thickness of the work, since with thicker work theelectrode pressure is built up to the switching pressure sooner in thecycle and is not relieved until later in the cycle. It will be seen thatchanges in the work thickness have the effect in Fig. 5e of raising andlowering the dotted lines indicating the pressure periods, thus varyingthe cyclic position at which the make and break of the switching occur.Similar effects may be produced for a given work thickness by theadjustments of the plate 51 or of the nuts 35, 36, 45 and 46 asdiscussed above.

In the alternative embodiment of the invention illustrated in Figs. 6through 8, many features are employed in common with the foregoingmachine of Fig. 1 and many of the remaining features are exactly thereverse of the corresponding features in that machine.

In Fig. 6, an outsole and welt 91, with an interposed layer ofthermoactive adhesive, are shown in position between electrode members92 and 93 and being engaged by work-feeding members 94 and 95. The upperelectrode member 92 is grounded to the frame of the machine andundergoes movements similar to those of the presser foot 8 of Fig. 1,whereas the lower insulated electrode member 93 is connected to thehigh-frequency oscillator 119 through wire 98'and is embedded in, andsubstantially flush with, the upper surface of a supporting block 99 ofinsulating material, and, together with the block 99, serves amechanical function similar to that of the support memher 9 in thatfigure. The block 99 is mounted on the frame of the machine by means ofa bolt 97. The work is fed intermittently by the work-feeding members 94and which are the mechanical counterparts of the corresponding electrodemembers 2 and 4 in Fig. 1.

Vertical motion is imparted to the foregoing members 94 and 95 by meanssimilar to the mechanism in Fig. 1, including a cam 100, opposing camplates 101 and 102, a link 103, and an upper offset rocker arm 106, thelatter including a bifurcated arm 107 which is pivoted on a shaft 198.Correspondingly, an upper collar 109 carried by the bifurcated arm 107transmits downward thrusts through a sleeve 109, a flanged member 110and a spring 111, to a lower flanged member 112, thereby yieldablypressing the upper feed member 94 against the work. Horizontal movementis imparted to the work-feeding members 94 and 95 through the action ofan eccentric in the lJ-shaped member 126 which operates to swing a yoke127 laterally back and forth and to slide the yoke up and down thesleeve 109.

The upper electrode member 92 is bolted to a downwardly projecting lug147 of an electrode carrier 137 which is mounted for verticalreciprocatory movement in a guideway. The carrier is held in theguideway by a cover 138 secured to the frame of the machine. Theelectrode carrier 137 receives its up-and-down motion through the actionof a lifting lever 128 which is pivoted to reciprocate about a mountingpin 131. One end of the lever 128 is connected to the yoke 127 by aslot-andpin connection similar to that of Fig. 1 while the other end ofthe lever 128 carries a pin'132 which engages a slot 133 in a headmember 134 of a vertical rod 135 slidable in the carrier 137. A spring136 and stop collars 139 and 140 associated with the rod 135 functionsimilarly to the corresponding members in the machine of Fig. 1 toprovide a spring biased lost motion connection between the lifting lever128 and the electrode carrier 137. In the manner of the former machine,the cyclic movements of the parts are derived through the rotation ofthe cam 100 and the eccentric 125. Four representative positions of thework engaging member are shown with reference to the position of theeccentric 125. In Fig. 8a, the work-feeding members 94 and 95, inseparated position, have nearly reached their rear or rightmost positionpreparatory to closing on the Work while the electrode members 92 and 93are shown gripping the work but are about to separate. In Fig. 8b, theelectrode members have separated and the work-feeding members havegripped the work preparatory to advancing the work to the left. In Fig.8c, the electrode mem- '7 bers have again descended upon the work andthe work'- feeding members are about to separate therefrom and return totheir starting position; and, in Fig. 8d, the workfeeding members havejust separated and have commenced their return motion toward thestarting position.

In Fig. 7 the two lowermost members shown in cross section represent theupper electrode member 92 and the upper feed member 94. The insulatingblock 99 has an outwardly extending shoulder adapted for engagement withthe welt crease. The lower supporting member 95 is likewise adapted forengagement with the welt crease. Both members are rounded back fromtheir outer shoulder portions to permit free sliding action of the shoerelative thereto.

In order to supply electric energy to the electrode only during the timethat it is pressed against the work, a switch 114, connected to controlthe operation of an oscillator 119, is mounted on the head member 134 bymeans of a screw 113, an actuating plunger 116 for the switch projectingdownwardly. A screw having a flat head 115 is threaded into the top ofthe electrode carrier 137 in such a position as to engage the plunger116 and operate the switch to turn on the oscillator upon the occurrenceof relative movement between the head 134 and the electrode carrier 137upon the yielding of the spring 136 under the pressure of the electrodeupon the work surface. As the lifting lever 128 is reciprocated to liftthe bar 135, the lost motion provided by the lostmotion connectionbetween the lifting lever and the elecnode is taken up and the switch114 is operated to cause the oscillator to become inoperative before theelectrode member 92 is lifted from the work. The wire connections 117and 118 between the switch 114 and the oscillator 119 complete thecontrol circuit (not shown)-of the latter. The oscillator is connectedto the upper and lower electrodes respectively by means of conductors121 and 98, the former being grounded to the frame of the machine at120.

Adjustments may be made in the machine of Fig. 6 as in the machine ofFig. 1, for example, to adjust the normal vertical position of theelectrode 92, the precompression in the spring 136, or the position ofthe screw head 115 with respect to the switch plunger116. For example,precompression may be adjusted by varying the position of the collars139 and 140 on the rod 135. Precompression of the spring 111 may beadjusted by means of nuts 142, 143, 145 and 146.

In the operation of either of the foregoing embodiments, the operatorinserts the work between the electrode and work-holding members, turnson the driving power and A thereafter guides the work, for example, bymaintaining the welt crease on a shoe continuously against guide members such as electrode 4 and the support 9. If desired the electrodeswitching may be so adjusted that the oscillator is never turned onunless there is a workpiece beneath the electrode.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent of the United States is:

1. In a dielectric progressive bonding machine, a frame, a shaft mountedfor rotation in said frame, a lifting cam carried by said shaft, anelectrode mounted for vertical reciprocation in said frame toward andaway from a work surface, an oscillator connected to said electrode, alifting lever pivoted to said frame, and operatively connected to saidlifting cam, said lever having a connection with said electrodeproviding lost motion after the electrode descends on the work surface,and a switch connected to control the operation of said oscillator andarranged to be operated by relative movement between the said lever andsaid electrode during such lost motion.

2. In a dielectric progressive bonding machine, a frame, a shaft mountedfor rotation in said frame, a lifting cam carried by said shaft, anelectrode mounted for vertical movement in said frame toward and awayfrom awork surface, an oscillator connected to said electrode, a liftinglever pivoted to said frame and operatively connected to said liftingcam, a vertically movable lifting member connected to be reciprocated bysaid lever, said member having a lost motion connection with saidelectrode providing lost motion after the electrode descends on the worksurface, a spring one end of which is associated with the lifting memberand the other with the electrode for yieldingly biasing said connectionin extended position, a switch connected to control the operation of theoscillator and arranged to be operated by relative movement between themember and said electrode during yielding of the spring, and means foradjusting the vertical position of that end of the spring associatedwith the lifting member relative thereto for adjusting the yieldingpressure of the spring without disturbing the heightwise position of theelectrode.

3. in a dielectric progressive bonding machine, a frame, a shaft mountedfor rotation in said frame, a lifting cam carried by said shaft, anelectrode mounted for vertical movement in said frame toward and from awork surface, an oscillator connected to said electrode, a lifting leverpivoted to said frame and operatively connected to said lifting cam, avertically movable lifting member connected to be reciprocated by saidlever, said member having a lost motion connection with said electrodeproviding lost motion after the electrode descends on the work surface,a spring one end of which is associated with the lifting member and theother end with the electrode for yieldingly biasing said connection inan extended position, a switch connected to control the operation of theoscillator and arranged to be operated by relative movement between themember and said electrode during yielding of the spring, and a stopmember limiting the extension of said lost motion connection to apredetermined amount, said stop member being mounted on and adjustablevertically of one of the parts so connected for simultaneously adjustingthe yielding pressure of said lost motion connection and the verticalposition of said electrode.

4. In a dielectric progressive bonding machine, a shaft mounted forrotation in said frame, a lifting cam carried by said shaft, anelectrode mounted for vertical movement in said frame for movementtoward and away from a work surface, an oscillator connected to saidelectrode, a vertically movable lifting member connected to bereciprocated by said cam, said member having a lost motion connectionwith said electrode, said connection providing lost motion after theelectrode descends on the work surface, a switch connected to controlthe operation of said oscillator and having contacts arranged inoperative association with said lifting member and said electrode tomake a circuit therethrough after a predetermined extent of lost motionhas occurred, and means for adjusting the said predetermined extent oflost motion.

5. In a machine for seaming dielectric material by the applicationthereto of a radio-frequency field, means for progressively feeding saidmaterial through said field, a reciprocatory electrode for periodicallyengaging said material, a stop to limit the material-engaging movementof said electrode, an oscillator, switch contacts for turning on and offsaid oscillator, a pivoted element carrying one of said contacts, meansfor directly actuating said element to periodically close and open saidcontacts, and a lost-motion link connecting said electrode with saidcontact-carrying element whereby said electrode is actuated after thelost. motion has been taken up by said link.

6. In a machine for seaming dielectric material by the applicationthereto of a radio-frequency field, an electrode, an oscillatorelectrically connected to said electrode to establish said field, aswitch mechanism for turning on and off said oscillator, means foroperating said switch mechanism periodically, link means providing alost-motion connection between said switch operating means and saidelectrode for imparting to said electrode a reciprocatory motion intoand out of said dielectric material in timed relation with the turningon and turning off of said oscillator, and stop means for limiting thetravel of said electrode into the work, said stop means cooperating withsaid 1ost-motion link to provide continued movement of said switchmechanism after the electrode has come to a stop in the material.

7. in an electronic seaming machine having a reciprocatory electrodeelectrically connected to a radio-frequency oscillator, and a movablepresser cooperating with a feed mechanism for advancing material pastthe electrode, a lift eccentric, a lifting lever operated by said lifteccentric, a switch operated by said lever for turning on and off saidoscillator, an electrode-bar carrying said electrode, and a lost-motionconnection between said lever and said electrode-bar for moving thelever to take up the lost motion and open the switch before theelectrode can begin its lift.

8. An electronic seaming machine comprising a frame, a shaft mounted forrotation in said frame, a cam carried by said shaft, a lifting leverpivoted in said frame and arranged to be rocked by operation of saidearn, an electrode-bar carried by said frame for vertical reciprocation,connecting means between said bar and said lever providing a lost-motionconnection therebetween, and first and second electrical contactsarranged to be opened and closed by cooperative action of said lever anda member arranged to engage the work during the opening and closing ofsaid contacts and arranged to be positioned by the work heightwisethereof in accordance with its thickness.

9. In a machine for seaming dielectric material by the applicationthereto of a radio-frequency field, means for progressively feeding saidmaterial through said field, a reciprocatory electrode for periodicallyengaging said material, an oscillator, switch contacts for turning onand off said oscillator, a pivoted element carrying one of saidcontacts, means for directly actuating said element to periodicallyclose and open said contacts, and a lost motion link connecting saidelectrode with said contactcarrying element whereby said electrode isactuated after the lost motion has been taken up by said link.

10. In a machine for sealing together plies of dielectric material bythe application thereto of a radio-frequency field, in combination,means for imparting intermittent feeding movements to said material,electrode means for applying pressure to and removing pressure from saidplies during said stationary periods, means including said electrodemeans for applying a radio-frequency field to and removing saidradio-frequency field from said plies in the region of the pressureapplication during each of said stationary periods, and adjustable meansfor con- 10 trolling the time of application of the pressure relative tothe application of the radio-frequency field.

11. In a machine for sealing together plies of dielectric material bythe application thereto of a radio-frequency field, in combination,means for imparting intermittent feeding movements to said material,electrode means for applying pressure to and removing pressure from saidplies during said stationary periods, means including said electrodemeans for applying a radio-frequency field to and removing saidradio-frequency field from said plies in the region of the pressureapplication during each of said stationary periods, adjustable means forcontrolling the time of application of the pressure relative to theapplication of the radio-frequency field, and independently adjustablemeans for controlling the time of removal of the pressure relative tothe removal of the radio-frequency field in each of said stationaryperiods.

12. In a machine for sealing together plies of dielectric material bythe application thereto of a radio-frequency field, in combination,means for imparting intermittent feeding movements to said material,means for holding said material stationary for a period between each ofsaid feeding movements, electrode means for applying pressure to andremoving pressure from said plies during said stationary periods, meansincluding said electrode means for applying a radio-frequency field toand removing said radio-frequency field from said plies in the region ofthe pressure application during each of said stationary periods,adjustable means for controlling the time of application of the pressurerelative to the application of the radio-frequency field, andindependently adjustable means for controlling the time of removal ofthe pressure relative to the removal of the radio-frequency field ineach of said stationary periods.

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